upgrade or another engine

[dave3235]

Hi everyone!
Having had my outfit for 2 years now I was looking at may be a bigger sib I currently have a 3.5 honwave with a 1988 20hp mariner mercury 2stroke, I am thinking of may be a 4.0 or 4.3.I don't realy want to sell the engine but was thinking of changing the carb from a 25hp or if poss a 30hp are there anything else that needs to be changed for these mods.I am aware that it may not be possible to convert to a 30hp but would be gratefull of any help

[spartacus]

Think there's always a little more to convert up, including different carbs, and possibly exhaust manifold. You'll need to see part lists for both engines to compare. Then there's the issue of selling it down the line. Reckon you'll have to convert it back for best price.

Few engines here, all 2-stroke, standard shaft.
1993 Mariner 25hp: http://www.seamarknunn.co.uk/download/usedob/used.pdf
Mariner 30hp: Buy Used Outboards 30.0HP Outboard at Bill Higham Marine
2008 Yamaha 25hp: 25hp yamaha 2 stroke, short, manual, tiller 2008 Boat Engines for sale in Lancashire, North West :: Boats and Outboards

A Zodiac 3.8m sib is perfect match with Yammie 25hp for power to weight ratio. Depends if you're trailering or building each time. If building, then 30hp is as big as I'd go.

[dave3235]

Thanks for the answer,but was hoping for may be exact things I would need to replace